Excavators and similar machines, such as those used in mining and quarrying are used for earthmoving material as moving and loading earth and stones. These machines are usually provided with a bucket or dipper attached to a mechanical arm. The bucket is provided with a blade or lip on a front edge for penetrating the ground and loading stones. To prevent excessive wearing of the blade and to aid penetrating the ground, it is common to assemble wear parts that protect the blade of the bucket. The wear parts may be teeth, adapters, shrouds or others. The wear parts can be fixed to the blade in different ways, such as welded, be part of the blade or be mechanically attached. The mechanical attachments have the advantage that they allow disassembling and assembling of the parts. Because said wear parts are subjected to wear and impacts too, they must be frequently replaced. Further, mechanical attachments do not need to use welding. On the other hand, the adapters are often welded to the blade of the bucket but they can also be mechanically attached, as in the present invention. The most common known adapters in the state of the art, specifically in mining, are the Whisler type adapters. In mining, the tooth and adapter assemblies work in hard abrasive and high impact conditions that require the replacement of the wear parts (teeth and adapters) frequently. Further, the blades of the excavators sometimes contain a high percentage of manganese that increases the hardness of the blade against impacts, but these blades do not allow welding. This type of adapter comprises a pair of arms that fit over the top and bottom surfaces of the blade of the excavator, including each arm of the adapter and blade holes that are aligned forming a channel. In said channel a C-clamp member and a wedge are introduced to lock the adapter on the blade. The wedge is inserted between the C-clamp member and the front of the channel pushing the C-clamp member rearwards and making that the legs of the C-clamp member exert pressure on the legs of the adapter, that press against the blade, securing the adapter to the blade. The insertion of the wedge is made by blows with a hammer.
This way of securing the adapter and the blade is time-consuming. Furthermore, an important aspect is that in mining works the security is very important, and during the mounting and removing process of the locking device to mount or replace the adapter, the wedge can fly out of its position with the resulting risk for the workers around. Further, under heavy loading the locking device gets lost and as such the adapter. In some occasions to prevent the mentioned problems, and once the wedge is introduced, the same is welded to the C-clamp member or welded to a front element place between the front of the channel and the wedge, as in prior art document U.S. Pat. No. 4,357,765. Welding different parts of the locking system makes, among other problems, the removal of the locking device and the removal of the adapter more difficult.
In the state of the art several documents try to solve the problem of inserting and removing the locking device from the assembly using hammerless systems. Two examples of hammerless systems are described in WO2008140878A1 and U.S. Pat. No. 7,299,570B2. Both solutions include a thread between the wedge and the front structure, in WO2008140878, or between the wedge and the C-clamp member, in U.S. Pat. No. 7,299,570. In this second patent document, the wedge is conically shaped with a thread that engages a thread on the C-clamp member, so that when the wedge is rotated, the same goes in and out of the channel, assuring the position of the locking system and of the adapter over the blade. Patent application WO2008140878A1 describes a locking system that comprises a wedge with a thread that engages a front structure with a screw. A stem on the top part of the front structure makes the screw rotate and therefore the wedge can go in and out of the channel.
Both embodiments require for removing the locking system to unscrew the wedge along its whole length making said operation time consuming and difficult as the thread will probably be filled with sand that makes its turning difficult.
The present invention allows an easy insertion of the locking system in the channel between an adapter and the blade of a bucket, but also solves the problems of the prior art regarding the removal of the locking system without the need to unscrew the wedge all along its length and neither use a hammer.